Lubricant-related performance characteristics such as high temperature deposit control, high temperature viscosity control, and oxidation control are extremely advantageous attributes as measured by a variety of bench and engine tests.
Lubricant-related viscosity and oxidation control performance is highly desirable due to the onset of smaller and higher output modern engine designs. These smaller, higher output, higher efficiency engines are emerging in new vehicle designs as a result of increasingly stringent governmental regulations for vehicle fuel consumption and carbon emissions. Lubricants need to provide a substantial level of high-temperature deposit and cleanliness performance while maintaining good viscosity and oxidation control due to the onset of smaller and higher output modern engine designs.
It is known that some metals (e.g., Fe or Cu) may catalyze oxidation reactions that negatively impact viscosity control in a lubricant. Furthermore, metal-containing detergents (e.g., Na, Ca, and Mg) are often added to a lubricant formulation to provide cleanliness performance, as well as serve as an alkalinity reserve to neutralize acidic oxidation products in the lubricant. Without sufficient levels of metal-containing detergents, high temperature performance issues may arise such as piston deposits, ring sticking and general valve train deposits and sludge. Conversely, an increase in metal-catalyzed oxidation reactions and decrease in viscosity control can be undesirable consequences of higher levels of detergent in an engine oil formulation.
Therefore, a major challenge in engine oil formulation is simultaneously achieving high temperature deposit control and cleanliness, while also controlling metal-catalyzed viscosity increases and oxidation.
Despite advances in lubricant oil formulation technology, there exists a need for an engine oil lubricant that effectively improves oxidation stability and viscosity control while maintaining or improving cleanliness performance and deposit control. In addition, there exists a need for an engine oil lubricant that effectively improves oxidation stability and viscosity control while maintaining or improving cleanliness performance, deposit control and fuel efficiency.